[cwittich] 39314: -check for filesize in MmCanFileBeTruncated -make use of MmCanFileBeTruncated in VfatSetAllocationSizeInformation -make use of MmCanFileBeTruncated in VfatSetInformation (patch by arty with some fixes from me) thanks to Alex for the hint that we miss the MmCanFileBeTruncated check fixes "Anyone has referenced a cache segment behind the new size." See issue #712 for more details.

Author: cwittich
Date: Tue Feb  3 06:39:55 2009
New Revision: 39314

URL: http://svn.reactos.org/svn/reactos?rev=39314&view=rev
Log:
-check for filesize in MmCanFileBeTruncated
-make use of MmCanFileBeTruncated in VfatSetAllocationSizeInformation
-make use of MmCanFileBeTruncated in VfatSetInformation (patch by arty with some fixes
from me)
thanks to Alex for the hint that we miss the MmCanFileBeTruncated check
fixes "Anyone has referenced a cache segment behind the new size."
See issue #712 for more details.

Modified:
    trunk/reactos/drivers/filesystems/fastfat/finfo.c
    trunk/reactos/ntoskrnl/mm/section.c

Modified: trunk/reactos/drivers/filesystems/fastfat/finfo.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/drivers/filesystems/fastfa…
==============================================================================
--- trunk/reactos/drivers/filesystems/fastfat/finfo.c [iso-8859-1] (original)
+++ trunk/reactos/drivers/filesystems/fastfat/finfo.c [iso-8859-1] Tue Feb  3 06:39:55
2009
@@ -548,10 +548,7 @@
    Fcb->RFCB.FileSize.QuadPart = Size;
    Fcb->RFCB.ValidDataLength.QuadPart = Size;
 
-   if (FileObject->SectionObjectPointer->SharedCacheMap != NULL)
-   {
-      CcSetFileSizes(FileObject, (PCC_FILE_SIZES)&Fcb->RFCB.AllocationSize);
-   }
+   CcSetFileSizes(FileObject, (PCC_FILE_SIZES)&Fcb->RFCB.AllocationSize);
 }
 
 NTSTATUS
@@ -692,6 +689,17 @@
   }
   else if (NewSize + ClusterSize <= Fcb->RFCB.AllocationSize.u.LowPart)
   {
+
+    DPRINT("Check for the ability to set file size\n");
+    if (!MmCanFileBeTruncated
+      (FileObject->SectionObjectPointer,
+      (PLARGE_INTEGER)AllocationSize))
+    {
+      DPRINT("Couldn't set file size!\n");
+      return STATUS_USER_MAPPED_FILE;
+    }
+    DPRINT("Can set file size\n");
+
     AllocSizeChanged = TRUE;
     /* FIXME: Use the cached cluster/offset better way. */
     Fcb->LastCluster = Fcb->LastOffset = 0;
@@ -891,6 +899,26 @@
   DPRINT("FileInformationClass %d\n", FileInformationClass);
   DPRINT("SystemBuffer %p\n", SystemBuffer);
 
+  /* Special: We should call MmCanFileBeTruncated here to determine if changing
+     the file size would be allowed.  If not, we bail with the right error.
+     We must do this before acquiring the lock. */
+  if (FileInformationClass == FileEndOfFileInformation)
+  {
+      DPRINT("Check for the ability to set file size\n");
+      if (!MmCanFileBeTruncated
+         (IrpContext->FileObject->SectionObjectPointer,
+          (PLARGE_INTEGER)SystemBuffer))
+      {
+         DPRINT("Couldn't set file size!\n");
+         IrpContext->Irp->IoStatus.Status = STATUS_USER_MAPPED_FILE;
+         IrpContext->Irp->IoStatus.Information = 0;
+         IoCompleteRequest(IrpContext->Irp, IO_NO_INCREMENT);
+         VfatFreeIrpContext(IrpContext);
+         return STATUS_USER_MAPPED_FILE;
+      }
+      DPRINT("Can set file size\n");
+  }
+
   if (!(FCB->Flags & FCB_IS_PAGE_FILE))
     {
       if (!ExAcquireResourceExclusiveLite(&FCB->MainResource,

Modified: trunk/reactos/ntoskrnl/mm/section.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/mm/section.c?rev=…
==============================================================================
--- trunk/reactos/ntoskrnl/mm/section.c [iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/mm/section.c [iso-8859-1] Tue Feb  3 06:39:55 2009
@@ -4714,10 +4714,10 @@
 MmCanFileBeTruncated (IN PSECTION_OBJECT_POINTERS SectionObjectPointer,
                       IN PLARGE_INTEGER   NewFileSize)
 {
- 
    /* Check whether an ImageSectionObject exists */
    if (SectionObjectPointer->ImageSectionObject != NULL)
    {
+      DPRINT1("ERROR: File can't be truncated because it has an image
section\n");
       return FALSE;
    }
 
@@ -4730,15 +4730,29 @@
 
       if (Segment->ReferenceCount != 0)
       {
-         /* FIXME: check if NewFileSize <= current file size */
+          /* Check size of file */
+          if (SectionObjectPointer->SharedCacheMap)
+          {
+             PBCB Bcb = SectionObjectPointer->SharedCacheMap;
+             if (NewFileSize->QuadPart <= Bcb->FileSize.QuadPart)
+             {
+                return FALSE;
+             }
+          }
+      }
+      else
+      {
+         /* Something must gone wrong
+          * how can we have a Section but no 
+          * reference? */
+         DPRINT1("ERROR: DataSectionObject without reference!\n");
          return FALSE;
       }
    }
 
-   /* FIXME: check for outstanding write probes */
-   UNIMPLEMENTED;
-
-   return FALSE;
+   DPRINT1("FIXME: didn't check for outstanding write probes\n");
+
+   return TRUE;
 }